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The joint essential numerical range of operators: convexity and related results

Chi-Kwong Li, Yiu-Tung Poon (2009)

Studia Mathematica

Let W(A) and $W_{e} (A)$ be the joint numerical range and the joint essential numerical range of an m-tuple of self-adjoint operators A = (A₁, ..., Aₘ) acting on an infinite-dimensional Hilbert space. It is shown that $W_{e} (A)$ is always convex and admits many equivalent formulations. In particular, for any fixed i ∈ 1, ..., m, $W_{e} (A)$ can be obtained as the intersection of all sets of the form $c l (W (A ₁, . . ., A_{i + 1}, A_{i} + F, A_{i + 1}, . . ., A ₘ))$ , where F = F* has finite rank. Moreover, the closure cl(W(A)) of W(A) is always star-shaped with the elements in $W_{e} (A)$ as star centers....

The numerical radius of a weighted shift operator with geometric weights.

Chien, Mao-Ting, Nakazato, Hiroshi (2009)

ELA. The Electronic Journal of Linear Algebra [electronic only]

The numerical radius of Lipschitz operators on Banach spaces

Ruidong Wang (2012)

Studia Mathematica

We study the numerical radius of Lipschitz operators on Banach spaces. We give its basic properties. Our main result is a characterization of finite-dimensional real Banach spaces with Lipschitz numerical index 1. We also explicitly compute the Lipschitz numerical index of some classical Banach spaces.

Displaying 81 – 88 of 88

The joint essential numerical range of operators: convexity and related results

The numerical radius of a weighted shift operator with geometric weights.

The numerical radius of Lipschitz operators on Banach spaces

Total decomposition and block numerical range.

Tracial numerical ranges and linear dependence of operators.

Геометрия области Хаусдорфа в задачах локализации спектра произвольных матриц

Двойственность в спектральной оптимизации и числовые области семейства самосопряженных операторов

Унитарный точечный спектр почти унитарных операторов

Currently displaying 81 – 88 of 88